Unveiling the Rarity: Pleural Metastasis of Papillary Thyroid Cancer – A Case Report and Clinical Implications

Papillary thyroid cancer (PTC) is an epithelial malignancy arising from the follicular cells within the thyroid, typically slow-growing with a benign course (5-year survival >99% in locally contained malignancies). However, in unusual cases, this condition can spread to the pleura, leading to a malignant pleural effusion. The authors present a case of an 80-year-old female presenting with dyspnoea following treatment for suspected bacterial pneumonia. Imaging revealed a substantial left-sided pleural effusion. Despite interventions such as thoracentesis and intravenous antibiotics, the pleural effusion persisted. Subsequent video-assisted thoracic surgery revealed pleural biopsies positive for PTC, a disease previously believed to have been cured almost 6 decades ago. Pleural involvement in patients with PTC is exceptionally rare. A literature review conducted between 1992–2023 revealed merely seven published reports documenting PTC metastasis to the pleura. The authors’ case emphasises the significance of exploring various potential causes of a patient showing signs of subacute dyspnoea, particularly in individuals previously diagnosed with PTC, as it emphasises the possibilities of unforeseen recurrence, featuring the uncertainties and complexities of managing PTC.